Clast/Grain sizes are much larger and more angular closer to the source. As the clasts move downstream they are slammed against each other and the stream bed breaking off into smaller clast and breaking off their sharp edges. Clasts gradually become rounded  and as the water slows, sorting the pebbles and cobbles and forming mounds/bars of gravel. If the gravel sits long enough it will undergo chemical weathering consequently sending individual mineral grains further downstream. Clay is so fine it may remain suspended in the water and carried downstream however sand may drop out and along the stream beds/banks where the water slows. Over time, the sand will lost feldspar and end up being composed almost entirely of quartz.

To summarize:

As sediments move downstream:

1) grain size gets smaller

2) clasts start out angular and are slammed into each other becoming less and less angular and more spherical. The further downstream, the more spherical the grain. The physical bouncing and grinding that accompanies the transport of sediment progressively rounds the quartz grains and sorts them.

3) as the waters slow, larger clasts are deposited in the form of gravel closest to the source, then sand falls or accumulates, then clay eventually may accumulate in the flat areas bordering the streams.

1) Shale - clay flakes are more or less parallel to the bedding. Under low-grade metamorphic conditions and differential stress it transforms into slate.

2)Slate - clay flakes are larger and better formed and align with the cleavage. As grade increases, new crystals of fine-grained mica form and crystals of chlorite and quartz form transforming into phyllite.

3) Phyllite - the minerals in phyllite react and decompose yielding atoms that produce large crystals of mica as well as other minerals like garnet. The reaction releases water, it escapes. Because this is happening under differential stress, micas grow with preferred orientation and the rock becomes a schist.

4) Schist - because this is under high grade conditions, it does not contain much mica if any. As the mica disappears (loses its -OH), the rock loses its schistosity but can develop a gneissic layering. Typicall includes water-free minerals like feldspar, quartz and garnet.

5) Gneiss - light colored layers contain predominantly felsic minerals like quartz and feldspar dark layers contain mostly mafic minerals like amphibole,biotite.

Sand-sized:

1/16-2.0mm clasts

compacts by 10-20%

meadium-coarse clasts

rounded or angular fragments

dominant grains of quartz, feldspar

lithified as sandstone

Clay-sized:

<1/256mm clasts

compacts by 50-80%

very fine clasts of clay or fine silt

lithified as shale

plate-like shape

1) Vibration

2) changes in slope characeristics

3) changes in slope strength

Triggers are not necessary for movement.

1- Anticline traps - oil is trapped in the archlike fold of the layers. if the layers in the anticline include a source rock overlain by a reservoir rock, overlain by a seal rock, the oil and gas rises from the source rock, into the reservoir rock and into the crest of the anticline where they are trapped.

2 - Fault Trap - the fault is in a fracture in which sliding has occured. Oil can be trapped if the slip grinds the adjacent rock to make an impermeable layer along the fault or against the reservoir rock, oil and gas can migrate upward along the bedding and get trapped.

3-Salt Dome Trap - salt layer rises through the overlying strata and creates a salt dome. As the dome rises, it bends up adjacent layers os sedimentary rock. Oil and gas migrate upward and get trapped against the boundary of the salt dome.

4- Stratigraphic trap - a tilted reservoir rock bed pinches out between two impermeable layers. Oil and gas migrate up and accumulate in the pinchout.